There are many applications in academic, industrial, and medical fields that benefit from devices and methods that are capable of accurately and controllably delivering fluids, such as liquids and gases that have a beneficial effect when administered in known and controlled quantities. Such devices and methods can be particularly useful in the medical field where treatments for many patients include the administration of a known amount of a substance at predetermined intervals.
Insulin-injecting pumps have been developed for the administration of insulin for those suffering from both type I and type II diabetes. Some insulin injecting pumps configured as portable infusion devices can provide continuous subcutaneous insulin injection and/or infusion therapy for the treatment of diabetes. Such therapy may include the regular and/or continuous injection or infusion of insulin into the skin of a person suffering from diabetes, and offers an alternative to multiple daily injections of insulin by an insulin syringe or an insulin pen. Such pumps can be ambulatory/portable infusion pumps that are worn by the user and that may use replaceable cartridges. Examples of such pumps and various features that can be associated with such pumps include those disclosed in U.S. patent application Ser. No. 13/557,163, U.S. patent application Ser. No. 12/714,299, U.S. patent application Ser. No. 12/538,018, U.S. patent application Ser. No. 13/838,617, U.S. patent application Ser. No. 13/827,707 and U.S. Pat. No. 8,287,495, each of which is incorporated herein by reference.
Infusions pumps such as those described above deliver medicament to patients through infusion sets that include tubing extending from the pump and a cannula with an associated needle that penetrates the patient's skin to allow infusion of the medicament through the cannula and into the patient. The cannula typically is held in place on the patient's skin with an adhesive patch. If the patch loosens from the patient's skin, the cannula can become disconnected from the patient, preventing the patient from receiving the medicament and potentially causing serious health concerns. In the case of insulin pumps, in many circumstances the flow of insulin through the cannula is relatively low, so the insulin may evaporate prior to contacting the patient's skin adjacent the insertion site such that the patient does not notice that insulin is not being received.
Therefore, there is a need for a system and a method that can automatically and reliably identify when an infusion set has become dislodged from a patient's skin.